1. Field of Invention
The present invention relates to an adjustable cable pulling apparatus and method used for pulling cable, and more particularly, to a cable puller for moving cable through the interior compartments of marine vessels.
2. Description of the Related Art
Electricians and large crews during both shipyard installations and maintenance operations are often required to pull large diameter cables. In the past, the installation of cable in Naval ships has been difficult because Naval ships are highly compartmentalized and watertight for good survivability characteristics in case of battle damage. Since the advent of electricity on ships, electrical cable has been run throughout the ship compartment bullheads via small pipe-like fittings that have compression rings to press against the cable to make an airtight/watertight seal. These fitting through which the electrical cable is threaded are called stuffing tubes. The stuffing tubes make installation and removal of electrical cables very labor intensive. The primary cause of difficulty is the coefficient of friction created between the rubber or plastic outer cable covering and the steel hangers used to support the cable, and stuffing tubes through which the cable must traverse.
The cable pulling operation typically requires several workers in each compartment passing the cable hand-over-hand within the compartment and through the stuffing tubes. It is similar to a bucket brigade except workers are reaching over their head while standing on scaffolding, which makes the job difficult, slow, and dangerous for the workers involved. As many as 30-100 workers may be involved in a single cable pulling operation. The cable must often make tight xe2x80x9cSxe2x80x9d turns to be properly routed. Moreover, the process must be well coordinated to avoid damage to the cable and personnel.
The cables are both long and heavy. The weight of the cables increases linearly as a function of how much cable is spooled out through the ship, which in turn makes handling difficult, time consuming and creates a high risk for back/shoulder and hand injury.
Conversely, pulling long runs of cable through electrical ducts in land-based applications is accomplished using a sequence of winches with one or more capstan wheels. The capstan wheel is driven by an individual electrical or hydraulic motor that turn the capstan wheels and pulls the cable through the electrical duct. Although these types of cable pullers have been quite effective in pulling cable in land-based applications. However, the land-based cable pullers are not portable or versatile enough to be easily adapted for use below the decks of a marine vessel. An example of a typical land-based cable puller is in U.S. Pat. No. 5,464,193 to Wrate which discloses a portable wire pulling device that can be secured into pulling position and easily released. The device has, in part, a housing and a frame with vertical hollow posts, a sheave between the posts, a motor driven capstan mounted on the housing and control power. The device can be run on AC or DC power, or can be used to charge internally mounted DC batteries. A number of pulling speeds can be obtained, depending on the type of control and selection device used. However, this large portable device has been designed for land-based applications and would not be easily adapted for pulling cable on a marine vessel where it is likely the device would need to be mounted off the ground or from a ceiling structure in confined spaces and moved from compartment to compartment.
More recently, there have been electrical cable pulling devices and systems that have been adapted to be used in marine applications. U.S. Pat. No. 5,624,207 to Berges discloses a marine seismic cable deployment and retrieval system for utilization in conjunction with a marine vessel. The system consists of a large wheel mounted on the vessel""s deck for retrieving seismic cable from the water, and a horizontally deck-mounted cable handler comprising an eight wheel cable puller for pulling cable. The cable puller is comprised four pairs of tires in rotational contact configured to frictionally grab and pull a seismic cable along a linear path. A smaller rear cable puller further urges the cable to the rear of the vessel, and down into the main deck via a chute arrangement. However, this cable puller is large and takes up significant space on the deck of the vessel, which would make the cable puller difficult to adapt to internal ship cable pulling operations below deck. Additionally, the cable pullers are permanently anchored to the deck and are not designed to be moved around the deck or different level decks for multiple cable pulling configurations.
Although these inventions may be useful as cable pulling apparatus in special applications, they do not represent the most efficient and economical way of achieving the desired results.
It is an object of the present invention to overcome the limitations of the prior art systems by providing a small, adjustable cable pulling apparatus and method that can pull and thread electrical cable through the interior compartments of a marine vessel easily and safely.
It is another object of the present invention to provide a cable pulling apparatus that can be mounted in a variety of different cable pulling configurations.
Still another object of the present invention is to maximize the speed and efficiency of pulling electrical cable through the interior compartments of a marine vessel.
Another object of the present invention is to minimize the inconveniences and size of present cable pulling devices. The cable puller of the present invention is both lightweight (weighing less than 60 pounds) and portable. It can be carried on and off the job site manually by only a single worker, if necessary.
It is an object of the present invention to provide a cable pulling apparatus that can be adapted for different size electrical cable.
It is another object of the present invention to improve the safety of pulling electrical cable through the interior compartments of a marine vessel by taking what was once a manual task and providing a degree of automation to significantly reduce the number of workers necessary to complete a cable pulling operation.
In accomplishing these and other objectives of the present invention, there is provided a cable pulling apparatus having a frame and a first roller driven by a power source rotatably mounted to the frame. A second roller is rotatably mounted to the frame and spaced from the first roller to allow an electrical cable to pass therebetween. A plurality of drive gears are engaged with the power source and at least the first roller to transfer a motive force of the power source to at least the first roller. Means adjust the spacing between the first and second rollers to increase or decrease friction forces between the cable and the first and second rollers.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.